Experts' take on high temperatures

Extreme heat events have now become the new normal

Wei Ke

Since the first day of 2023, extreme heat events have increased the threat to human health and the environment. Europe experienced the warmest New Year in history, with temperatures in some places reaching early summer levels. The highest temperature, of 25.1 Celsius, was recorded in Bilbao, Spain. In Glucholazy, Poland, the temperature at 4 am on Jan 1 was as high as 18.7 C, more than the local average minimum summer temperature. And while at least eight European countries experienced their hottest New Year's Day, more than 100 weather stations in France reported record-breaking temperatures.

Unlike gradual global warming which many people expect, extreme heat events have raised temperatures to historical highs in many places. On Jan 1 this year, temperatures in many places in France, Germany, Denmark and Latvia were exceptionally high. For example, the temperature in Berlin, Germany, was 16 C — normally, it hovers around 0 C during New Year.

According to the State of the Global Climate 2022 of the World Meteorological Organization, which was released on April 21, global temperatures in 2022 were 1.15 C higher compared with the pre-industrial levels from 1850 to 1900. Global warming is not a gradual and uniform process anymore; instead, it manifests through a succession of extreme heat events, continuously breaking high-temperature records worldwide.

There has been a significant increase in both the frequency and intensity of extreme heat events. According to the UN Office for Disaster Risk Reduction's report, Human Cost of Disasters 2000-19, there were 432 instances of extreme heat events globally between 2000 and 2019 compared with just 130 instances between 1980 and 1999, an increase of a whopping 232 percent.

As the northern hemisphere enters the summer season, extreme heat events have become the norm, rather than the exception. On April 14, Tak province in northwestern Thailand recorded a scorching 45.4 C, breaking Thailand's highest temperature record of 44.6 C set in Mae Hong Son province in 2016.

Record-breaking heat-waves have swept across Southeast Asia, South Asia and Central Asia, with temperatures crossing 42 C. And severe air pollution has further compounded the situation in many parts of Southeast Asia, and thus increased the risk of respiratory and cardiovascular diseases.

The impacts of high temperatures are far-reaching, not only affecting human life and health but also posing a threat to the environment and ecosystems. In 2020, more than 330 elephants in the southern region of Botswana died of cyanotoxin poisoning, as prolonged heat and drought led to a bloom of cyanobacteria in ponds and other water bodies. These cyanobacteria released a significant amount of cyanotoxins in the water bodies, which resulted in the poisoning and subsequent deaths of the elephants that consumed the toxic water.

Extreme heat and drought also contribute to wildfires. In 2019-20, Australia experienced severe heat waves that contributed to the devastating wildfires which lasted for a staggering nine months. While the wildfires caused an economic loss of about 10.3 billion Australian dollars ($6.73 billion), they also claimed the lives of or displaced nearly 3 billion animals — mammals including marsupials, birds, reptiles and amphibians.

Worse, the wildfires emitted about 715 million tons of carbon dioxide, more than Australia's total annual greenhouse gas emissions from fossil fuel combustion.

One of the worst effects of global warming is the "wet gets wetter, dry gets drier" phenomenon, where humid regions experience increased rainfall and arid regions become drier — with the rainy season marked by more severe flooding and the dry season by intense drought.

According to the Human Cost of Disasters 2000-19 report, over the past 20 years, there has been a 134 percent increase in flood-related disasters, 97 percent increase in storms, 46 percent increase in wildfires, and 29 percent increase in droughts or drought-like conditions.

In addition, as the oceans warm, heat-waves emanating from the oceans and seas have become more common. The increasing warming of the ocean surface inhibits the absorption of oxygen by the water, which exacerbates the problem of oxygen depletion in the marine environment, posing a threat to the survival of marine animals and plants. Warmer ocean temperatures also contribute to the increasing frequency and severity of typhoons and hurricanes. And since such storms have a wider range extending to northern latitudes, regions like northeastern China could experience typhoons in the future.

In summer, extreme heat conditions in the northern hemisphere are becoming the norm, prompting the WMO to urge countries to issue early warnings and take early action. But while it is essential for governments and management agencies at all levels to issue weather alerts and forecasts, they should also pay greater attention to the rights of vulnerable groups, including people who work outdoors during hot weather.

Building public heat shelters to protect people during orange and red heat alerts is essential. Especially, public activity centers, libraries and other government facilities allow outdoor workers to avoid working during the hottest hours of the day. As for people in general, they should closely follow weather forecasts and warnings so they can avoid the risk of heatstroke by not venturing out during extreme heat events.

Yet global temperatures will continue to rise as greenhouse gas emissions are unlikely to reduce drastically in the next 20-30 years. Therefore, economies around the world, especially the major economies, should intensify efforts to reduce emissions. The public, on its part, can contribute to the global efforts to mitigate climate change by adopting simple habits including switching off lights when not in use, recycling products, reducing the use of cars, changing the food habit, and refraining from compulsive shopping. These slight changes in habits can help lower individuals' carbon footprint and thus reduce emissions.

But global cooperation is needed to bolster society's resilience to extreme heat and enhance its capacity to overcome climate challenges.

The views don't necessarily reflect those of China Daily.